Field of the Invention
The present invention relates to an image processing apparatus that determines whether read image data is image data having printing information or image data of a blank sheet having no printing information.
Description of the Related Art
At the time of reading an original by an image reading apparatus such as a digital copying machine, there is a skimming-through method for reading an image while feeding the original by an auto document feeder (ADF) in a state where the position of an optical system is fixed.
Conventionally, in a copying machine with an auto document feeder, even when an original whose both sides are printed and an original whose one side is printed are mixed, both sides are read.
In this method, however, the blank face of the back side of the original whose one side is printed is also read. As a result, by reading the blank sheet having no printing information, unnecessary data is processed. Consequently, wasteful sheet consumption and power consumption occur. To address the problem, Japanese Patent Application Laid-Open No. 2010-178377 discusses a technique of suppressing useless printing and wasteful consumption of a sheet and toner by eliminating image data of a blank sheet determined by using a blank-sheet detection function of detecting whether a read original is a blank sheet having no printing information.
Japanese Patent Application Laid-Open No. 2010-178377 discusses a blank-sheet determination method for detecting an edge part in image data read from an original and determining whether the original is a blank sheet having no printing information, from the ratio of the detected edge amount to the number of pixels of a whole page.
Japanese Patent Application Laid-Open No. 2005-27088 discusses a method for stopping output when a blank sheet is detected in the case of copying an original by using the technique of blank-sheet detection. According to Japanese Patent Application Laid-Open No. 2005-27088, when a page including image data determined as a blank sheet is detected in a process for reading an image of an original, printing of the page is stopped, and the stop is notified to the user. By the method, unnecessary printing of a blank sheet is prevented (hereinbelow, called a blank-sheet skip printing function).
On the other hand, a digital copying machine in recent years has a sheet insertion function of inserting a divider sheet or interleaving paper. When the function is used, a color sheet, a tub sheet, or the like can be inserted in a position desired by the user in a printed matter, so that the value addition of the output matter can be increased. When the user designates an insertion position, a common method is designating a page number. For example, the insertion position (page) is designated by a designation method such as “before fourth page” in a printed matter. When the user desires to insert an insertion sheet in a plurality of places, a plurality of pages is designated. It is also possible to determine whether an image of an original is copied to an insertion sheet. For example, when an insertion sheet is not included in advance in an original, a mode of “not printing in an insertion sheet” is selected. In this case, a blank insertion sheet (having no printing information) is inserted. On the contrary, when an insertion sheet is included in an original, a mode of “printing in an insertion sheet” is selected. In this case, an original image is copied also to the insertion sheet.
However, in the case of simultaneously using the blank-sheet skip printing function and the insertion sheet function, a problem occurs such that the insertion position of an insertion sheet designated by the user is changed. As described above, the insertion position of an insertion sheet is instructed by designating a page number in a printed matter. However, when a blank sheet page is skipped without printing the blank-sheet, the page number in an output printed matter is changed, and the relative insertion position of an insertion sheet is changed. Further, a problem occurs also with respect to the mode of “printing in an insertion sheet”. When an insertion sheet having no printing information, such as a blank sheet or a color sheet, is inserted in an original, if the page is determined as a blank sheet and printing is skipped by the blank-sheet skip printing function, an image which is not originally an insertion sheet is handled as an insertion sheet, and a printing result which is not desired by the user is obtained.